An association has been noted between cancer of the uterine cervix and cigarette smoking after controlling for other known risk factors. In this epidemiologic study we propose to use the Ames/Salmonella microsomal test on cervical fluids of 330 smokers and 330 nonsmokers to determine whether smokers are more likely to have a positive outcome for mutagenicity. Subjects for this study will be accrued by two community-based physicians who will collect the specimens themselves to assure data-collection uniformity. To collect the specimen, the cervix is washed with 1 ml of sterile nonpyrogenic electrolyte solution, the fluid is drawn into a pipette, the wash is repeated and the fluid is then again drawn into the pipette, placed in a test tube and frozen. A randomly chosen subsample of 30 smokers who were positive on their laboratory tests will be asked to return to the clinic to have another specimen taken. They will refrain from smoking for 14 hours prior to mucus specimen collection, be asked to smoke, wait one hour, and then have a second specimen obtained. Patients will be interviewed before fluid collection by a professional interviewer. The structured questionnaire will cover smoking habits, passive smoking environment, sexual history, contraceptive use, history of sexually transmitted diseases, and recent diet. The Ames test will be done after an adequate number of specimens have been collected from the medical practices. Laboratory work will be conducted by the Lawrence Livermore National Laboratory. Statistical analyses will be conducted by the Northern California Cancer Program using the IBM PC-XT and statistical software purchased by the epidemiology unit. We will examine the relationship between laboratory results and exposure characteristics using methods developed by Mantel and Haenszel. We also will use the multiple-logistic model to assess possible interaction, to control for potentially confounding variables, and to obtain point estimates and confidence limits for the relative risk of each variable under study.